Skate boots for ice skates or in-line land based skates are well known. The majority of conventional skate boots are made from molded synthetic resins. Traditional molded in-line skates, as illustrated by FIG. 1, include a single pivot axis between the lower boot (which receives and constrains a foot) and an upper cuff (that grips the lower leg). The pivot axis is often a rivet-type connection on each side of the boot, providing a joint located in the vicinity of the anatomical ankle joint.
Conventional boots allow for rotation of the ankle, called flexion-extension-extension (shown by the curved arrow in FIG. 1). The boots are stiff in the lateral direction to provide support for maneuvering during skating. Unfortunately, the single pivot is difficult to locate exactly at the ankle joint, which is understood by those skilled in biomechanics to lie generally along an axis through the bony protuberances on the side of the ankle. The amount of force required to move the lower leg (the tibia) with respect to the ankle about this pivot axis during the skating motion (flexion-extension) can accordingly be more than it would otherwise be. The material of the boot must often be deformed to obtain a full range of motion for the user's ankle.
To complicate the problem, the anatomical pivot joint actually “floats” as the angle between the foot and the lower leg changes in the flexion-extension motion. More particularly, neither the lower leg nor the foot are made up of a single bone structure, and the connection between the foot and lower leg is more complicated than that of a simple hinge. The anatomical pivot point accordingly shifts in relationship to the axis through the bony protuberances on the side of the ankle as the angle of the foot relative to the lower leg shifts. A boot pivot axis created by a rivet-type connection, however, is fixed in the position of the rivet.
Another disadvantage of using the current rivet-type technology is that all of the load transferred at the pivot joint is concentrated at the pivots. The material around these pivots on both the upper cuff and the lower boot must accordingly be built up. While the extra material resists unwanted boot deflection due to longitudinal, lateral and torsion loads, it also results in more costly manufacture, heavier boots and concern for long term fatigue problems.
There are other problems and limitations with the current boot technology. The cuff must extend low enough to reach under the pivot axis, as well as extend high enough to grip the lower leg at a height that provides an adequate and comfortable lever arm. The lower boot must extend high enough above the pivot axis to support the pivot loads. Thus the cuff and lower boot have size and load requirements that add to the weight of the boot, add to the cost of manufacture, and adversely impact heat dissipation.
In fact, the design requirements of the single hinge approach to the flexion-extension issue restrict the number of options available to a boot designer. Once the cuff and lower boot height and weight considerations are met, there is little room for creative, alternative boot designs.
Most in-line skates have a rear mounted brake pad fixed to the lower boot behind the rear wheel. Braking occurs when the skater lifts the front of the skate off the rolling surface to engage the brake pad with the surface. More recently, movable brake mechanisms have been introduced, such as the two link chain extending between the cuff and the rear wheel comprising the brake depicted in FIG. 1. The rotation of the cuff clockwise relative to the boot (which is accomplished by the skater sliding a foot forward along the road surface while keeping the wheels on the road) will bring the brake pad in contact with the road surface. A shortcoming of the two link brake system, however, arises because two extra links must be added to the boot cuff and lower boot to realize the braking function. Also, the mechanical advantage of the two link brake is limited and nearly constant during braking.
A skate that would reduce the total weight of the boot, reduce the cost of manufacture, reduce the effort to rotate the ankle in flexion-extension during skating, and reduce the molded material surface and associated heat build up, would be a decided improvement to conventional designs. A new design that could incorporate flexures (living hinges) as substitutes for riveted joints would further reduce manufacturing costs. A new skate design would advantageously increase design options and should provide the ability to customize boots for a single person or a grouping of individuals based on leg, ankle and foot anatomy, and other preferences such as boot weight, anticipated use of the skates (recreational, racing, hockey, tricks, etc.), and the ankle strength of the user. Finally, an integrated brake design that avoided the problems of adding more complexity to the standard boot and limited control of the mechanical advantage would provide lower cast and safety, as well as other advantages over conventional systems.